Mercury float relay



June 12, 1956 J. R. PATTERSON 2,750,466

MERCURY FLOAT RELAY Filed May 12, 1953 limited States Patent MERCURY FLOAT RELAY .llames R. Patterson, Shreveport, La.

Application May 12, 1953, Serial No. 354,456

1 Claim. (Cl. 20G-112) This invention relates to an electromagnetically actuated relay of the mercury-to-mercury contact type.

An important object of the present invention is to provide a relay of the character referred to which can be used for any of various purposes, such as a signal relay utilized with telephone signal devices, motor control circuit relays, and as a relay for pressure systems, alarm systems, etc.

A further object of importance is to provide a relay as stated which will be so designed as to permit one form of the device to be utilized as either a normally open relay, or as a normally closed relay, whichever is desired.

Another object of importance is to provide a relay which will have distinct advantages as compared to a conventional relay of the type having metal contact points, the relay constituting the present invention closing a circuit only by means of a mercury-tomercury bridging of the terminals of the device, thus eliminating the burning and sticking of metal contact points which occurs in relays of conventional design. A further advantage is found in the present invention through the use of a floattype plunger, which eliminates spring devices usually required on relays to hold the contacts in a normally open or normally closed position.

Another object of importance is to provide a mercury float relay as stated which will be particularly adapted for use in multiple, the construction which I have designed being such as to permit a single electromagnetto control the opening or closing, as the case may be, of a number of relay devices formed in accordance with the present invention.

Summarized briefly, the present invention comprises a casing having a mercury reservoir partitioned into side by side mercury compartments, said compartments communicating with one another above the partitioning means employed. A plunger is shiftable into and out of one of said compartments, said plunger being adapted, when shifted into its associated compartment, to displace the body of mercury contained therein and raise the level of said body of mercury above the partitioning means, vthus to cause the bodies of mercury in side by side compartments to be brought into communication with one another, thereby to provide a mercury-to-mercury bridge between terminals dispo-sed in the respective compartments. The plunger is carried by a medially fulcrumed rocker arm having an armature at one end attrached by an electromagnet. The rocker arm is so designed as to permit the plunger to be connected thereto at either side Vof the fulcrum point, thus to cause the plunger to be lifted out of the compartment associated therewith on attraction of the armature by an electromagnet, or cause the plunger to be shifted into a compartment on attraction of said armature, whichever is desired according to the needs of the particular situation.

Other objects will appear from the following descrip tion, the claim appended thereto, and from the annexed 2,750,466 Patented June l2, 1956 drawing in which like reference characters designate like parts throughout the several views, and wherein:

Figure l is a longitudinal sectional view through a mercury float relay formed in accordance with the present invention;

Figure 2 is a top planview;

Figure 3 is a plan sectional view taken substantially on line 3f3 of Figure 1;

Figure 4 is a vertical sectional View taken transversely through the device on lin 4-4 of Figure 1;

Figure 5 is a fragmentary perspective view showing the midlength portion of the rocker arm;

Figure 6 is an elevational View ofthe plunger, per se;

Figure 7 is a. fragmentary longitudinal sectional view through the device, showing the means employed to hold the parts in a predetermined position during shipment thereof; and

Figure 8 `is a view similar to Figure l, showing the plunger adjusted to a different position upon the rocker arm.

The reference numeral 1() has been applied in the drawing to designate a flat, rectangular support plate 1? of electrically insulative material. The support plate, of course, would be adapted for mounted upon any suitable supporting surface.

Fixedly mounted upon one end of the support plate lt) is a casing 12. Casing 12 is also of electrically insulative material, and could be of plastic, glass, or the like. Preferably, the material used for the casing would be one that is not unduly aifected bythe heat generated by the arc occurring during the make or break.

vFormed in the casing 12 isa reservoir 14. A transverse partition 16 integral with the bottom wall of the reservoir rises upwardly therein a suitable distance above the reservoir bottom, and divides the reservoir into a pair of side by side compartments adapted to contain mercury 13. The compartments, as shown in Figure l, communicate with one another above the upper end of the partition.

Formed in the casing are openings through which extend terminal screws 20, the heads of said screws being disposed in the lower ends of the respective mercury compartments, and the other ends of the screws being projected through suitable openings formed in the support plate 10, and being 'provided with nuts 22 for holding upon the screws electrical leads 26. Between the heads of the screws and the adjacent bottom surfaces of the compartments rubber washers 24 are interposed, in a preferred embodiment of the invention.

It will be understood that the leads 26 are in circuit with a source lof electricity, and lit will further be understood that one of the leads can extend Vfrom an electrical device 28 also in circuit with said source of electricity, thus to energize said device whenever the terminals 20 are bridged.

A cover plate for the casing has been designated by the reference numeral 30, and is 'of electrically insulative material, said cover plate being secured flxedly to the vupper end of the casing by means of screws 32 or equivalent fastening elements.

Integral or otherwise made rigid with the cover plate, intermediate the opposite ends thereof, is a bracket 34 ,(Figure 4) of inverted U shape, and extending upwardly from the bight ofthe bracket are spaced ears 36 having transversely aligned openings through which a pivot pin 3S extends.

An elongated rocker arm 40 has, intermediate its ends, a transversely extending enlargement 42 having an aperture through which pin 38 extends, the rocker arm being thus fulcrumed for rocking movement about a horizontal axis extending transversely thereof. Adjacent the enlargement 42, the underside of the rocker arm is provided with transversely spaced ears 44, said ears having aligned 'openings A pair of transversely spaced ears 46 is formed upon rocker arm 40 at the other side of enlarge- Iment 42, the ears 46 also being provided with aligned vopenings.

In the arm 40 an opening 48 is provided, at the 1ocation of ears 44. An opening 50 is formed in the rocker arm at the location of ears 46, either of these openings being adapted for extension therethrough of the stem 52 of a plunger having a conical tip 54. A rubber washer 56 is circumposed about stem 52, and abuts against the base of said tip, for a purpose to be made presently apparent.

An opening 58 is provided in the cover plate 30, adjacent bracket 34, the stem 52 being loosely positioned through said opening, and having up and down movement in the opening. Intermediate the opposite ends of the stern, a transvere aperture 60 receives a Cotter key 62.

The Cotter key 62 is adapted to be inserted through the apertures of ears 44 or 46, and when connected to ears 46 as in Figure 1, disposes the plunger in a normally depressed position, forming the relay into one of the nor- `mally closed type. When, however, the cotter key 62 'is used for connecting the plunger pivotally to ears 44, the plunger will be normally held in a raised position, `forming the relay into one of the normally open type. The versatility of the structure is thus increased meas- -urably, as will be readily apparent.

Carried by one end of the rocker arm 40 is a Weight 64 mounted upon a relatively short extension arm 65 that is secured to the adjacent end of the rocker arm 40 by means of a screw 66, said extension arm having a lonlll gituclinal slot 68 through which the screw extends, thus to permit the extension arm to be shifted longitudinally of the rocker arm for the purpose of adjusting the balance thereof. The arm 40 is thus capable of being maintained in a predetermined normal position regardless of the particular location thereon at which the plunger is disposed.

On that end of the rocker arm remote from weight 64, I provide an armature 70, said armature being disposed above an electromagnet 72 mounted on support plate 1t) adjacent casing 12. Normally, the electromagnet is de-energized, but it will be understood that whenever it is energized, it will attract armature 76, thus to 'rock arm 4G, as shown in Figures l and 8, in a clockwise direction about its pivot axis. If the plunger is disposed as in Figure 1, swinging of the rocker arm in this manner will cause the tip of the plunger to be elevated out of the body of mercury. The mercury level will thus drop, causing the mercury-to-mercury bridge between the terminals Z0 to be broken. The circuit including said `terminals is thus opened, and will remain open until such time as the electromagnet 72 is de-energized. This will be effective to cause the tip 56 to be shifted once again into the mercury 18, closing the circuit through the terminals.

If the plunger is disposed as in Figure 8, that is, between ythe fulcrum point of the rocker arm and the armature 70, the plunger will be normally disposed in an elevated position. When the electromagnet is energized, the plunger will be depressed into its associated compartment, thus displacing the mercury contained therein and raising the level of the mercury to an extent sufficient to cause a mercury-to-mercury bridge between the terminals 20. It becomes apparent, accordingly, that the device, though made in a single form, can be used as either a normally yopen or normally closed relay.

In Figure 7 I have illustrated the means whereby the Idevice can be prepared for shipment. A problem which arises in connection with the shipment of a relay of the mercury type has to do with the loss of the mercury. Accordingly, when the device is to be shipped a spring '74 is circumposed about the upper end of the plunger stem, said spring abutting at one end against the rocker arm 40 and at its other end against a washer 76 circumposed about the upper end of the stem and held in position by a cotter key 78 extended through a small transverse opening 80 formed in the stem.

Spring 74, tending to expand, urges the stern upwardly from the rocker arm, simultaneously causing the rocker arm to be shifted ntoengagement with the electromagnet. The cork washer' 56 is thus pressed against the cover plate 30, sealing the opening 58 of the cover plate.

At such time as the device is to be placed in use, the Cotter key is removed, and the spring 74 and washer 76 are also removed. A Cotter key is then employed to pivotally connect the plunger to the ears 44 o-r 46, as the cae may be.

It will be understood that in transferring the plunger connection from ears 44 to 46, or vice versa, one would also reverse the cover plate 30 unless the cover plate has more than one opening 58.

It is believed apparent that the invention is not necessarily confined to the specific use or uses thereof described above, since it may be utilized for any purpose to which it may be suited. Nor is the invention to be necessarily limited to the specific construction illustrated and described, since such construction is only intended to be illustrative of the principles of operation and the means presently devised to carry out said principles, it being considered that the invention comprehends any minor change in construction that may be permitted within the scope of the appended claim.

What is claimed is:

A mercury float relay comprising: a casing having a mercury reservoir and including a partition extending upwardly Within the reservoir to divide the same into a pair of side by side mercury compartments communicating with one another above the partition; terminal means in the bottoms of the respective compartments; a rocker arm fulcrumed on the casing above and substantially midway between said compartments and including an armature spaced from its fulcrum point; a plunger depending from said arm in alignment with and arranged to shift into and out of one of said compartments responsive to rocking of the arm about its fulcrum, thus to displace a body of mercury in said one compartment to raise the level thereof above the partition and bring the same into communication with a body of mercury in the other compartment, thereby to provide a mercury-to-mercury bridge between the terminal means; and electromagnetic means located adjacent said armature and controlling movement of the plunger.

References Cited in the tile of this patent UNITED STATES PATENTS 623,511 Bouchet Apr. 25, 1899 1,393,701 Sanchez Oct. 11, 1921 1,653,283 Hood Dec. 20, 1927 1,897,132 Leins Feb. 14, 1933 2,522,717 Hottenroth Sept. 19, 1950 2,541,571 Clapp Feb. 13, 1951 FOREIGN PATENTS 295,745 Germany Dec. 16, 1916 637,201 Germany Oct. 23, 1936 117,724 Australia Nov. 3, 1943 

